JOOMLA: J15 di PHP 5.4 WORK!!!!

PADA SAAT INSTALASI:
(sumber: http://stackoverflow.com/questions/7771128/error-while-install-joomla)
In xampp/php/php.ini change

    1.display_errors=Off
    2.error_reporting = E_ALL & ~E_NOTICE & ~E_WARNING

Then restart your xampp


KALAU SUDAH JALAN:

Paste kode berikut di index.php, di home dan administrator:

// Set flag that this is a parent file
define( '_JEXEC', 1 );
error_reporting( E_ERROR | E_PARSE | E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_COMPILE_WARNING );

sumber: http://forum.joomla.org/viewtopic.php?f=429&t=271244&start=30